PR target/19599
* config/arm/predicates.md (call_insn_operand): New predicate.
* config/arm/constraints.md ("Cs", "Ss"): New constraints.
* config/arm/arm.md (*call_insn, *call_value_insn): Match only
if insn is not a tail call.
(*sibcall_insn, *sibcall_value_insn): Adjust for tailcalling through
registers.
* config/arm/arm.h (enum reg_class): New caller save register class.
(REG_CLASS_NAMES): Likewise.
(REG_CLASS_CONTENTS): Likewise.
* config/arm/arm.c (arm_function_ok_for_sibcall): Allow tailcalling
without decls.